Why do you have to use ALT ON - what's the point of Mode C altitude returns when you're taxiing?
Well its standard practice here.
Radar targets taxying around the airport are filtered out below 300 ft to avoid clutter.
Transponder is required to be on to enable A-SMGCS to operate but without Mode C the altitude is unknown and therefore not filtered, causing nuisance targets.
Don't know enough about TCAS to comment on the TA/RA thing.
At our unit we receive a flashing notification of an RA and then (hopefully) a COC.
Interesting Pringle_.
How is that downlinked? Via Mode S?
Was that function always there or only after Uberlingen?